Li-Ion Conductivity Enhancement of LiBH<sub>4</sub>·<i>x</i>NH<sub>3</sub> with <i>In Situ</i> Formed Li<sub>2</sub>O Nanoparticles
Wanying Zhao, Ruixue Zhang, Hongjiao Li, Yunsheng Zhang, Yao Wang, Chaoling Wu, Yigang Yan, Yungui Chen
Abstract
Interfacial engineering is an efficient approach to improve the ionic conductivity of solid-state electrolytes. In the present study, we report the enhancement of in situ formed nanocrystalline Li2O on the thermal stability and electrochemical properties of amide lithium borohydride, LiBH4·xNH3 (x = 0.67–0.8). LiBH4·xNH3–Li2O composites with different amounts of Li2O are prepared by a one-step synthesis process by ball milling the mixture of LiBH4, LiNH2, and LiOH in molar ratios of 1:n:n (n = 1, 2, 3, 4). Owing to the strong interfacial effect with nanocrystalline Li2O, LiBH4·xNH3 is converted to the amorphous state in the presence of 78 wt % Li2O at n = 4. Consequently, the ionic conductivity of LiBH4·xNH3 at 20 °C is improved by orders of magnitude up to 5.4 × 10–4 S cm–1, the NH3 desorption temperature is increased by more than 20 °C, and the electrochemical window is widened from 0.5 to 3.8 V.